There is still a little bit of blood on the ninth day of menstruation, and coitus is not recommended on the tenth day. If a woman in the ninth day of menstruation there is a little bit of blood, then the stripped endometrial trauma is still not fully repaired, at this time coitus is easy to lead to the upward movement of bacteria in the vagina, resulting in endometritis, pelvic inflammatory disease, etc.; and at this time coitus may also cause the menstrual blood reflux, which increases the probability of the occurrence of endometriosis. Women’s normal menstrual cycle is 2~8 days, if the 9th day still have a small amount of bleeding, this time also need to be alert to endometrial polyps, cervical polyps, endocrine disorders and other diseases, so it is recommended that women go to the regular hospital in time to improve the relevant examination, clear the cause of the cause of disease in the guidance of a professional doctor for targeted treatment.